European Concerted Action on Anticoagulation (ECAA): an assessment of a method for ISI calibration of two whole blood point-of-care PT monitor systems based on lyophilized plasmas using whole blood equivalent PT.
ABSTRACT Previously, the attempt to simplify the International Sensitivity Index (ISI) calibration of the CoaguChek Mini whole blood point-of-care test prothrombin time (PT) monitor system was successful using lyophilized plasmas from coumarin-treated patients but not with lyophilized artificially depleted plasmas. With the TAS PT-NC monitor system, both types of plasma failed to provide reliable calibrations. The present study assesses a procedure for the ISI calibration of a TAS PT-NC and CoaguChek Mini whole blood point-of-care test PT monitor systems using lyophilized plasmas. Using lyophilized artificially depleted and coumarin plasma calibrations, we have evaluated a correction for the monitor displayed PT. This was based on a 'line of equivalence' derived from the relationship between whole blood and fresh plasma PT with both types of monitor system. With the TAS PT-NC, the use of this 'line of equivalence' resulted in reliable ISI with both lyophilized coumarin and artificially depleted plasmas. There was no significant difference between mean monitor and mean reference International Normalized Ratio (INR) with the artificially depleted plasmas. With the lyophilized coumarin plasma calibrations there was only a small INR difference. Correction with the 'line of equivalence' therefore facilitates calibration of the TAS PT-NC with lyophilized plasmas. With the CoaguChek Mini, the correction based on the 'line of equivalence' did not improve results but was not required with this system.
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ABSTRACT: A system for quality assessment (QA) of the CoaguChek (Roche Diagnostics, Mannheim, Germany) point-of-care testing prothrombin time monitor has been developed by the European Concerted Action on Anticoagulation. Hitherto there has not been an adequate rapid method for CoaguChek QA. Sets of 5 certified international normalized ratio (INR) plasma samples were tested on 539 CoaguChek monitors by experienced staff at 9 Netherlands Thrombosis Centers and results compared with certified INR. A 15% or more deviation has been classified as significant deviation. Overall mean and certified INR values were similar, but 20.3% of participants showed a 15% or more deviation from the certified INR on at least 1 of the 5 QA plasma samples. Statistically significant differences in results with different lots of CoaguChek test strips were found. There is need for large scale QA of CoaguChek monitors. The importance of the 5 CoaguChek certified INR QA plasma samples being tested on a single occasion is demonstrated.American Journal of Clinical Pathology 12/2006; 126(5):756-61. · 2.88 Impact Factor
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ABSTRACT: The use of oral anticoagulant therapy is increasing in children. Managing anticoagulant therapy in children presents unique challenges, including poor venous access. The advent of point-of-care (POC) monitoring of anticoagulant therapy offers a potential solution to this challenge. This paper reviews the published literature relating to POC monitoring of oral anticoagulant therapy in children. A Medline search was conducted and identified key publications. Papers were reviewed with respect to their objectives, populations and POC device investigated. Study limitations were identified. Five publications and one abstract were identified, reporting studies using five different POC monitors. Three studies had a strong clinical management focus. Outcome measures assessed included target therapeutic range achievement and frequency of adverse events. Correlation between POC and laboratory-based results ranged from 0.83 to 0.96. Home monitoring and self-management using POC monitors were both reported to be preferred compared to standard laboratory testing. POC monitoring of oral anticoagulant therapy in children offers considerable advantages. The reviewed literature would suggest such monitoring can be performed accurately and reliably. The impact of quality control issues, such as calibration of thromboplastin ISI in POC devices, has not been explored in a paediatric population. Further studies are needed to clarify such issues and confirm the safety, reliability and efficacy of POC monitoring of oral anticoagulant therapy in children, including its home monitoring and self-management programs.Thrombosis Research 02/2006; 118(1):113-21. · 3.13 Impact Factor
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ABSTRACT: International Normalized Ratios (INRs) for prothrombin time obtained with the CoaguChek Mini and TAS (RapidPointCoag) PT-NC systems are markedly different and also differ from the "true" INR. There is therefore a need for local quality assessment (QA) of the two systems. A set of 60 lyophilized artificially depleted and 60 lyophilized coumarin plasmas were tested at 10 centers on both point-of-care testing monitors. Subsets of three and five plasmas were selected as QA plasmas and compared with the remaining 55 to assess the relative ability of the systems to characterize performance at the individual centers. The incidence of aberrant results (outliers; >15% deviation from the true INR) was also recorded. The expected incidence with the QA plasmas was calculated and compared. On both systems, INR with the common sets of 55 lyophilized plasmas varied considerably between centers. With the TAS PT-NC, subsets of five and three European Concerted Action on Anticoagulation (ECAA) artificially depleted plasmas gave good correlation with the 55 plasmas, but the coumarin plasmas performed less well. With the CoaguChek Mini, correlation was good with sets of five artificially depleted QA plasmas and reasonable with three but was less satisfactory with the coumarin plasmas. Outliers were detected with both types of plasmas on both test systems but with variable success. With the TAS PT-NC, three ECAA artificially depleted lyophilized plasmas provided reliable QA, but five lyophilized coumarin plasmas were required. With the CoaguChek Mini, five artificially depleted plasmas gave reliable QA but coumarin plasmas gave poorer results. ECAA QA plasmas provide a local system for checking INRs obtained with monitors of both types.Clinical Chemistry 04/2004; 50(3):537-44. · 7.15 Impact Factor